Significant Decrease In Entropy Research Articles

Treatment-related changes in neuroendocrine tumors as assessed by textural features derived from 68Ga-DOTATOC PET/MRI with simultaneous acquisition of apparent diffusion coefficient

BackgroundNeuroendocrine tumors (NETs) frequently overexpress somatostatin receptors (SSTRs), which is the molecular basis for 68Ga-DOTATOC positron-emission tomography (PET) and radiopeptide therapy (PRRT). However, SSTR expression fluctuates and can be subject to treatment-related changes. The aim of this retrospective study was to assess, which changes in PET and apparent diffusion coefficient (ADC) occur for different treatments and if pre-therapeutic 68Ga-DOTATOC-PET/MRI was able to predict treatment response to PRRT.MethodsPatients with histopathologically confirmed NET, at least one liver metastasis > 1 cm and at least two 68Ga-DOTATOC-PET/MRI including ADC maps were eligible. 68Ga-DOTATOC-PET/MRI of up to 5 liver lesions per patients was subsequently analyzed. Extracted features comprise conventional PET parameters, such as maximum and mean standardized uptake value (SUVmax and SUVmean) and ADC values. Furthermore, textural features (TFs) from both modalities were extracted. In patients with multiple 68Ga-DOTATOC-PET/MRI a pair of 2 scans each was analyzed separately and the parameter changes between both scans calculated. The same image analysis was performed in patients with 68Ga-DOTATOC-PET/MRI before PRRT. Differences in PET and ADC maps parameters between PRRT-responders and non-responders were compared using Mann-Whitney test to test differences among groups for statistical significance.Results29 pairs of 68Ga-DOTATOC-PET/MRI scans of 18 patients were eligible for the assessment of treatment-related changes. In 12 cases patients were treated with somatostatin analogues between scans, in 9 cases with PRRT and in 2 cases each patients received local treatment, chemotherapy and sunitinib. Treatment responders showed a statistically significant decrease in lesion volume and a borderline significant decrease in entropy on ADC maps when compared to non-responders. Patients treated with standalone SSA showed a borderline significant decrease in mean and maximum ADC, compared to patients treated with PRRT. No parameters were able to predict treatment response to PRRT on pre-therapeutic 68Ga-DOTATOC-PET/MRI.ConclusionsPatients responding to current treatment showed a statistically significant decrease in lesion volume on ADC maps and a borderline significant decrease in entropy. No statistically significant changes in PET parameters were observed. No PET or ADC maps parameters predicted treatment response to PRRT. However, the sample size of this preliminary study is small and further research needed.

Absolute value and diversity of household spending: analysis on International Comparison Program (ICP) 2011 data

Research background: This article investigates the connection between consumer?s budget growth and diversification of household spending. The main question of research is ?are there new drivers of modern processes of consumer spending's diversification, at a time when spending on food has reached the minimum share in the consumer budget.
 Purpose of the article: The objective of the article is to clarify the hypothesis about the existence of a certain limit of income (and consumer spending) after which the growing of consumer?s purchasing capacity loses power of influence on spending diversity.
 Methods: Theil entropy index was used for measuring the diversity of household spending. This index was defined as a sum of within-group and between-group entropy, which allows for comparing the diversification of household spending in two aggregate groups of expenditure, which were formed by the authors. The Workings? equation was used for modeling the spending entropy?s dependence on their absolute value. Two categories of household spending were regrouped (consolidated) by us through forming a group more related to the development of human economic potential (SMRHD) and less related to these processes (SLRHD). The research was done on the basis of ICP (2011) data, which covers 178 countries and refers to 2011 year ? the latest available on the moment of the article was completed.
 Findings & Value added: The results obtained in this research confirmed that there is a limit of household spending?s size, beyond which further increasing of consumers? economic opportunities loses a significant impact on the diversity of consumption spending. However, the weakening of the link between size of spending and its entropy reflects impact of two qualitative differenced factors. The first is relatively much more radical decrease of spending growth influence on within-group entropy for SLRHD. The second ? is relatively much less significant decrease of entropy?s sensitivity to spending growth for SMRHD. Such results reflect the increase in the importance of "non-functional demand components", which reduces the capacity of data on functional distribution of household expenditures to characterize the extent of their diversification.

The Intrinsically Disordered C. Trachomatis Tarp Binds Actin with a Partially Preformed Helix

Tarp (Translocated actin recruiting protein) is an intrinsically disordered protein (IDP) from Chlamydia trachomatis, which is translocated into the host cell via type III secretion to initiate the infection process. Once exposed to the cytosol, Tarp recruits host-cell actin, forming actin pedestal-like structures that contribute to host cell invasion (Clifton et al., PNAS101,10166). Tarp is capable of directly nucleating the formation of actin filaments, and its actin-binding region was mapped to the region between residues 726 and 825 (Jewett et al., PNAS103, 15599). We have acquired and assigned nuclear magnetic resonance (NMR) spectra of Tarp726-825, which show the narrow spectral distribution and chemical shifts characteristic of an IDP. Tarp shows some homology to the actin binding WH2 motif from WAVE2, and therefore it is expected to bind in a similar manner, forming a helix upon binding. Indeed, NMR relaxation experiments of Tarp726-825 show slightly lower flexibility in the 10-residue region homologous to the WH2 motif. However, chemical shift index calculations show that this helix is only partially formed before binding. In the presence of globular actin, the majority of peaks in the Tarp NMR spectra are affected, indicating that the binding affects most of the amino acid residues in this Tarp fragment. Isothermal titration calorimetry experiments determined the dissociation constant for the binding to be 1.02 (± 0.32) × 10−7 M, and showed a significant decrease in entropy upon binding, indicating increased order upon binding. Based on this information, the binding of Tarp to actin was modelled in silico. Two possible low energy sites of interaction have been identified, both of which could account for these observations. It is therefore possible that Tarp binds actin through a “fuzzy” interface, with contribution from both conformations.

Assessment of changes in tumor heterogeneity following neoadjuvant chemotherapy in primary esophageal cancer

To assess the changes in computed tomography (CT) tumor heterogeneity following neoadjuvant chemotherapy in esophageal cancer. Thirty-one consecutive patients who received neoadjuvant chemotherapy for esophageal cancer were identified. Analysis of primary tumor heterogeneity (texture) was performed on staging and post-chemotherapy CT scans. Image texture parameters (mean grey-level intensity, entropy, uniformity, kurtosis, skewness, standard deviation of histogram) were derived for different levels of image filtration (0-2.5). Proportional changes in each parameter following treatment were obtained. Comparison between pathological tumor response and texture parameters was analyzed using Mann-Whitney U-test. The relationship between CT texture and overall survival) was estimated using the Kaplan-Meier method. Tumor texture became more homogeneous after treatment with a significant decrease in entropy and increase in uniformity (filter 1.0 and 2.5). Pretreatment (filter 1.5, P = 0.006) and posttreatment standard deviation of histogram (filter 1.0, P = 0.009) showed a borderline association with pathological tumor response. A proportional change in skewness <0.39 (filter 1.0) was associated with improved survival (median overall survival 36.1 vs. 11.1 months; P < 0.001). CT tumor heterogeneity decreased following neoadjuvant chemotherapy and has the potential to provide additional information in primary esophageal cancer.

Formation and thermodynamic stability of novel methyl–vinyl derivatives of PtIV as possible intermediates for Csp3–Csp2 cross-coupling

Methyl–vinyl derivatives of PtIV were obtained in a sequence of the reactions of methyl iodide oxidative addition to PtII iodo complexes followed by iodoplatination of C–C triple bond of R1CCR2 (R1 = Ph, R2 = C(O)OC2H5; R1 = R2 = C(O)OCH3) in acetone solution under excess of I−. In the reaction of the ethyl phenylpropiolate equilibrium formation of PtIV methyl–vinyl derivative ▪ occurs. The reaction is highly exothermic, ΔH = –(81 ± 7) kJ/mol, and this provides a favorable thermodynamics even though a significant decrease in entropy, ΔS = −(249 ± 23) J/(K mol). In the reaction of dimethyl acetylenedicarboxylate the chelate metallocycle ▪ is quantitatively formed. The quantitative yield of the organometallic product is explained by more favorable thermodynamics of the reaction: chelation of the metal center by the oxygen atom of the carboxymethyl group in the σ-vinyl ligand forming metallocycle provides an additional stabilization of the product. In the formed organoplatinum compounds vinyl and methyl ligands are located in the mutual cis-positions, which is essential for further accomplishment of Csp3–Csp2 coupling reaction.

An Analysis of Eye Scanpath Entropy in a Progressively Forming Virtual Environment

A sign of presence in virtual environments is that people respond to situations and events as if they were real, where response may be considered at many different levels, ranging from unconscious physiological responses through to overt behavior, emotions, and thoughts. In this paper we consider two responses that gave different indications of the onset of presence in a gradually forming environment. Two aspects of the response of people to an immersive virtual environment were recorded: their eye scanpath, and their skin conductance response (SCR). The scenario was formed over a period of 2 min, by introducing an increasing number of its polygons in random order in a head-tracked head-mounted display. For one group of experimental participants (n = 8) the environment formed into one in which they found themselves standing on top of a 3 m high column. For a second group of participants (n = 6) the environment was otherwise the same except that the column was only 1 cm high, so that they would be standing at normal ground level. For a third group of participants (n = 14) the polygons never formed into a meaningful environment. The participants who stood on top of the tall column exhibited a significant decrease in entropy of the eye scanpath and an increase in the number of SCR by 99 s into the scenario, at a time when only 65% of the polygons had been displayed. The ground level participants exhibited a similar decrease in scanpath entropy, but not the increase in SCR. The random scenario grouping did not exhibit this decrease in eye scanpath entropy. A drop in scanpath entropy indicates that the environment had cohered into a meaningful perception. An increase in the rate of SCR indicates the perception of an aversive stimulus. These results suggest that on these two dimensions (scanpath entropy and rate of SCR) participants were responding realistically to the scenario shown in the virtual environment. In addition, the response occurred well before the entire scenario had been displayed, suggesting that once a set of minimal cues exists within a scenario, it is enough to form a meaningful perception. Moreover, at the level of the sympathetic nervous system, the participants who were standing on top of the column exhibited arousal as if their experience might be real. This is an important practical aspect of the concept of presence.

Structural and energetic aspects of the protonation of phenol, catechol, resorcinol, and hydroquinone.

The various protonated forms of phenol (1), catechol (2), resorcinol (3), and hydroquinone (4) were explored by ab initio quantum chemical calculations at the MP2/6-31G(d) and B3LYP/6-31G(d) levels. Proton affinities (PA) of 1-4 were calculated by the combined G2(MP2,SVP) method, and their gas-phase basicities were estimated after calculation of the change in entropy on protonation. These theoretical data were compared with the corresponding experimental values determined in a high-pressure mass spectrometer. This comparison confirmed that phenols are essentially carbon bases and that protonation generally occurs in a position para to the hydroxyl group. Resorcinol is the most effective base (PA = 856 kJ mol-1) due to the participation of both oxygen atoms in the stabilization of the protonated form. Since protonation is accompanied by a freezing of the two internal rotations, a significant decrease in entropy is observed. The basicity of catechol (PA = 823 kJ mol-1) is due to the existence of an intramolecular hydrogen bond, which is strengthened upon protonation. The lower basicity of hydroquinone (PA = 808 kJ mol-1) is a consequence of the fact that protonation necessarily occurs in a position ortho to the hydroxyl group. When the previously published data are reconsidered and a corrected protonation entropy is used, a proton affinity value of 820 kJ mol-1 is obtained for phenol.

Wavelet entropy in event-related potentials: a new method shows ordering of EEG oscillations.

In this work we show the application of a measure of entropy defined from the wavelet transform, namely the wavelet entropy (WS), to the study of event-related potentials (ERPs). WS was computed for ERPs recorded from nine healthy subjects with three different types of stimuli, among them target stimuli in a cognitive task. A significant decrease of entropy was correlated with the responses to target stimuli (P300), thus showing that these responses correspond to a more "ordered" state than the spontaneous EEG. Furthermore, we propose the WS as a quantitative measure for such transitions between EEG ("disordered state") and ERP ("ordered state").

Entropic stabilization of a mutant human lysozyme induced by calcium binding.

The stabilization mechanism of the mutant human lysozyme with a calcium binding site (D86/92) was investigated by using calorimetric approaches. By differential scanning calorimetry, the enthalpy change (delta H) in the unfolding of holo-D86/92 was found to be 6.8 kcal/mol smaller than that of the wild-type and apo-D86/92 lysozymes at 85 degrees C. However, the unfolding Gibbs energy change (delta G) of the holo mutant was 3.3 kcal/mol greater than the apo type at 85 degrees C, indicating a significant decrease of entropy (T delta S = 10.1 kcal/mol) in the presence of Ca2+. Subsequently, the Ca2+ binding process in the folded state of the mutant was analyzed by using titration isothermal calorimetry. The binding enthalpy change was estimated to be 4.5 kcal/mol, and delta G was -8.1 kcal/mol at 85 degrees C, which indicates that the binding was caused by a large increase in entropy (T delta S = 12.6 kcal/mol). From these analyses, the unfolded holo mutant was determined to bind Ca2+ with a binding delta G of -4.8 kcal/mol (delta H = -2.6 kcal/mol, T delta S = 2.2 kcal/mol) at 85 degrees C. Therefore, the major cause of stabilization of holo-D86/92 is the decrease in entropy of the peptide chain due to Ca2+ binding to the unfolded protein.